What is Photography?
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A term which comes from the Greek words photos (light) and graphos (drawing). A photograph is made with a camera by exposing film to light in order to create a negative. The negative is then used in the darkroom to print a photograph (positive) onto light-sensitive paper. Developed in the second half of the 19th century, this development was very important in astronomy. The first pictures of space were taken around 1840, but the methods of photography weren't important in astronomy until about twenty years later. But when they were used, they told us things we couldn't see before. Photographs of the Moon were used to draw atlases, sunspots were more easily recorded, details of nebulae and stars were found. In 1882, Sir David Gill photographed a comet and discovered that the picture showed tons of stars . . . a great way to map the sky. A process by which chemically sensitized surfaces are exposed to light (photo) and retain an image (graph) of what is exposed. Methods may be very simple to highly complex. Camera are usually used with adjustable lenses (apertures) and controlled light levels on light sensitive film. The film is then processed (developed) and the image is 'fixed' (made permanent). The image (a negative) is transferred onto treated papers, enlarged and processed with chemicals in a "dark room" to make the photographs (also called prints). |
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